1. Field of the Invention
This invention relates in general to electronic equipment and more specifically to EMI shielding for cable openings in electronic equipment housings.
2. Description of the Related Art
Communication system equipment and other types of electronic system equipment are required to meet rigid electromagnetic interference (EMI) emissions standards. In an ideal design, the electronic components of a communication system would be totally enclosed in an electrically conductive enclosure with no openings. However, due to a number of constraints including temperature considerations and data input and output, numerous openings are required in a communications system housing. Preferably, these openings should be minimized to reduce EMI emissions from a communications system.
Communication system equipment may utilize hundreds of fiber optic cables and other cables for providing data input and output to the system. To accommodate such a large number of cables, some system housings include large holes for multiple cables to pass through. However, providing large cable openings allows EMI emissions to pass through as well. Furthermore, communication systems typically include circuits operating at high frequencies which produce high frequency emissions. In order to block high frequency emissions, a communication system housing needs to have smaller openings.
One method for minimizing EMI emissions due to cable openings in a communication system housing is to provide an individual cable opening in the housing for each cable. However, one problem with this technique is that the cables may chaff at the sharp edged, entry points of the individual openings. Also, the number of individual holes that can be made is limited by the surface area of the housing.
Another solution for minimizing EMI emissions is to mount individual passthrough connectors in the housing for signals to pass through the housing. The signals of a cable are carried to the connector by a cable connected to the connector on the outer side of the housing and to the connector by a cable connected to the connector on the inner side of the housing. However, pass through connectors add expense to a communication system and take up space on the housing panels.
What is needed is an improved technique for reducing EMI emissions due to cable openings in electronic system housings.
Providing an electronic system housing with an EMI shield having deformable, electrically conductive material to define cable passageways advantageously provides EMI shielding for cable openings in an electronic system housing.
In one aspect, the invention includes an EMI shield having cable passageways. An EMI shield includes at least one portion made of a deformable electrically conductive material. The at least one portion defines a plurality of cable passageways extending from a first side of the at least one portion to a second side of the at least one portion. Each cable passageway is to receive a cable extending through from the first side to the second side.
In another aspect of the invention, an electronic system includes a housing having an opening and an EMI shield mounted in the opening. The EMI shield includes at least one portion made of a deformable electrically conductive material. The at least one portion defines a plurality of cable passageways extending from a first side of the at least one portion to a second side of the at least one portion. The electronic system includes a plurality of cables. Each of the plurality of cables extends through a passageway of the plurality of passageways.
In another aspect, the invention includes a method for providing EMI shielding for an electronic system housing. The method includes positioning a plurality of EMI shields in an opening of an electronic system housing. Each of the plurality of EMI shields including at least one portion made of a deformable electrically conductive material. The at least one portion defines a plurality of cable passage ways extending from a first side of the at least one portion to a second side of the at least one portion. The method also includes installing cables in the plurality of cable passageways of the plurality of EMI shields and compressing the at least one portions of the plurality of EMI shields with the plurality of cables installed in the passageways.
In another aspect of the invention, an electronic system includes a housing having an opening and an EMI shield mounted in the opening. The EMI shield includes deformable electrically conductive material and means for defining in the deformable electrically conductive material a plurality of cable passageways extending from a first side of the deformable electrically conductive material to a second side of the deformable electrically conductive material. Each cable passageway is for receiving a cable extending through from the first side to the second side.